Pressing tool and pressing process

ABSTRACT

A pressing tool for tightly pressing sleeve-like fittings ( 32   a ) includes a hydraulic cylinder device having a fork-like connecting part ( 7 ) and a drive motor. A pressing jaw ( 51 ) with a fastening pin ( 50 ) is fastened in the fork-like connecting part ( 7 ). A piston of the hydraulic cylinder device, which piston is connected to a piston rod ( 6 ), is moved out of the starting position in the cylinder by the drive motor. As a result, the piston rod ( 6 ) is extended from the cylinder. As a result of the movement of the piston rod ( 6 ), the cheek plates ( 51   a   , 51   b ) of the pressing jaw ( 51 ) are moved apart in the region of actuation surfaces ( 8   a   , 8   b ) of the cheek plates ( 51   a   , 51   b ) in order to press the cheek plates ( 51   a   , 51   b ) together in the region of the fittings ( 32   a ) to be pressed. In order to carry out a pressing process ( 44 ) safely, the pressing tool has, in the region of the fork-like connecting part ( 7 ), a presence sensor ( 52 ) which checks for the presence of the pressing jaw ( 51 ) and, in the case of an absent or incorrectly fastened pressing jaw ( 51 ), triggers a warning signal ( 45   a ) and, after a delay, switches off the pressing tool if a properly inserted pressing jaw ( 51 ) is still not present.

BACKGROUND OF THE INVENTION

[0001] 1. Field Of the Invention

[0002] The invention relates to a pressing tool and to a pressing process.

[0003] 2. Description of the Background Art

[0004] Pressing tools for tightly pressing sleeve-like fittings onto pipe ends must ensure that the pressing jaws always tightly press the fitting correctly. For the conventional fitting diameters, corresponding pressing jaws can be inserted in each case into the pressing tool. Because large forces are required for tight pressing, a hydraulic cylinder is used for actuating a pressing jaw in various known pressing tools. U.S. Pat. No. 5,125,324 discloses embodiments in which an electric motor drives a hydraulic pump. The pressurized liquid is fed into a hydraulic cylinder for actuating a piston which actuates the pressing jaw. By arranging the pump with electric motor directly on the hydraulic cylinder device, a compact actuation unit is formed. At the end of the pressing process, an excess pressure is generated in the cylinder and leads to opening of a pressure relief valve and hence to the end of the pressing process. Before the next pressing process, the piston is reset by a reset spring with recycling of the liquid into a collecting region. The pressing tools according to the prior art can be used with many different, changeable pressing jaws. The various pressing jaws are formed for pressing copper and steel fittings or for connecting plastics pipes having different diameters in each case.

[0005] For fastening the various pressing jaws, pressing tools have a fork-like connecting part in which the pressing jaws are inserted and are fastened to the pressing tool by means of a fastening pin. The various pressing jaws therefore have, in their connecting element, a hole through which the fastening pin is inserted. The connecting part likewise has a hole which receives the fastening pin and in which the latter is secured. The fastening pin must be completely inserted into the hole in the connecting part in order to ensure that the pressing tool functions satisfactorily. For various reasons, it is found again and again that the fastening pin is not properly inserted, and this has already led to accidents. The publication EP-0941813-A1 discloses a pressing tool which carries out a check to ensure that the fastening pin is locked during operation, in order to prevent such accidents. As long as the fastening pin is not properly secured, a warning signal is triggered. A presence check with respect to the pressing jaw is also performed. The disadvantage is that the pressing process as such is not terminated when a pressing jaw is missing or has been incorrectly inserted.

SUMMARY OF THE INVENTION

[0006] It is the object of the invention to make an improvement in the safety of such a pressing tool. In addition, a pressing process of the pressing tool should be capable of being triggered only when the presence of a pressing jaw has been ensured.

[0007] In achieving the object, it was recognized that the safety of the pressing tool can be increased by means of a pressing jaw presence check. In contrast to publication EP-0941813-Al, however, the pressing jaw presence check leads to the pressing tool being switched off if no pressing jaw is present or if the latter becomes detached from the pressing tool during the pressing process. The pressing jaw presence check is intended to be a check which also safely functions in the case of severe soiling and in a moist environment. It is therefore preferable to use a sensor which measures without contact and which makes it possible to determine a field property which is clearly distinguishable with present and absent pressing jaw.

[0008] For this purpose, it is possible to provide, for example on the pressing jaw, a presence magnet which is detectable by a presence Hall sensor of the pressing tool. Because old pressing jaws or pressing jaws from other manufacturers should also be capable of being used, it is however advantageous to use for the presence check an inductive sensor which makes it possible to detect the presence of any pressing jaw. However, it is also possible to use other sensors or mechanical switches which respond on contact.

[0009] With such a sensor for the presence check, it is possible to carry out a pressing process in which the pressing can be carried out safely using all usable pressing jaws. In the pressing process, initialization steps or initialization tests are envisaged after the pressing tool has been switched on. Before it is possible to trigger the pressing process, a presence check is carried out to determine whether a pressing jaw has been inserted or not. If no pressing jaw is present, an acoustic and/or optical warning signal is triggered and the presence check is then carried out again. If, after a delay, a pressing jaw still has not been inserted or has been poorly inserted, the pressing tool is switched off or the pressing process cannot be triggered. In order to trigger a pressing process again, the pressing jaw must be introduced into the pressing tool and fastened to the pressing tool by means of the fastening pin. If a pressing jaw was already present, it must be ensured that the pressing jaw is correctly inserted into the connecting part. If the presence control detects that a pressing jaw has been inserted, an allocation check is carried out after a short delay. If there is no allocation, a standard range or standard values is or are assigned, as described in detail in the publication EP-0941813-A1. Thus, this publication states that a piston position range value is assigned to the piston connected to the piston rod, which value corresponds to the pressing jaw used in each case. The instantaneous piston position is detected by a measuring means and compared with the piston position range value. If the value for the instantaneous piston position and the piston position range value agree, or the instantaneous piston position is within a tolerance range around the piston position range value, the pressing procedure is found to be satisfactory; otherwise, pressing is recognized as incorrect.

[0010] As a further check before the triggerability of a pressing process is enabled, a locking check is carried out. For carrying out the locking check, the pressing tool has at least one locking sensor measuring without contact. If the fastening pin is not locked or is not in the securing position, this is detected by the locking sensor and indicated at least by means of an acoustic and/or optical warning signal. Optionally, the locking check is repeated until the fastening pin is locked or secured. After a delay to enable the operator to carry out the locking of the fastening pin properly, the pressing tool may be ready for triggering a pressing process.

[0011] Before it is made possible for a further pressing process to be triggered, the sequence already described above and comprising a pressing jaw presence check, which detects whether a pressing jaw has been inserted or not, a locking check and an allocation check is carried out again. In order to ensure that a pressing jaw cannot be removed and then a pressing process triggered after these checking steps, the checking steps are repeated at specified time intervals optionally at least during the triggering actuation for a pressing process. If no pressing process is triggered for a specified maximum rest time, the pressing tool is switched off.

BRIEF DESCRIPTION OF THE DRAWINGS The drawings illustrate the invention purely by way of example with reference to an embodiment.

[0012]FIGS. 1a and 1 b show a connection region of a pressing tool with inserted pressing jaw and secured fastening pin and

[0013]FIG. 2 shows a flow diagram for the pressing process.

DETAILED DESCRIPTION OF THE INVENTION

[0014]FIG. 1a shows a fork-like connecting part 7 of a pressing tool, FIG. 1b a section thereof, comprising a piston rod 6, pressing rollers 28 and a guide block 29 which is guided in a linear guide 30. The linear guide 30 is fastened to a cylinder part 5 and has, in the region of the fork-like connecting part 7, a hole 31 for receiving a fastening pin 50 by means of which a pressing jaw 51 is fastened. The pressing jaw 51 consists of a fastening part 51 c, which is connected to a connecting element 51 d, and in which two cheek plates 51 a and 51 b are each pivotably mounted about an axis 9 a and 9 b of rotation, which axes 9 a and 9 b of rotation are at right angles to the plane of the drawing. The cheek plates 51 a and 51 b have actuation surfaces 8 a and 8 b which rest against the pressing rollers 28 during a pressing process 44 (cf. FIG. 2). The actuation surfaces are formed in such a way that the pressing rollers 28 moving forwards cause the cheek plates 5 a and 51 b to move together, by means of pivot movements about their axes 9 a and 9 b of rotation, in the region of a fitting 32 a to be pressed, the fitting 32 a being inserted into an orifice 32 in the pressing jaw 51 together with the pipe ends to be connected.

[0015] In order to permit a pressing jaw presence check 45 (cf. FIG. 2), a presence sensor 52 measuring without contact is preferably arranged in the linear guide 30 in such a way that it makes it possible to determine a field property which is clearly distinguishable with present and absent pressing jaw 51. For this purpose, a presence magnet which is detectable by a Hall sensor as a presence sensor 52 of the pressing tool can be provided, for example on the pressing jaw 51. Preferably, however, an inductive sensor is used, which makes it possible to detect the presence of any metal pressing jaw 51, even if no presence magnet is provided in the pressing jaw 51. Alternatively, however, it is also possible to use a sensor responding to contact, such as, for example, a pressure sensor, or a mechanical switch as presence sensor 52. If the pressing jaw 51 is present, it must also be ensured that the fastening pin 50, which connects the pressing jaw 51 to the pressing tool, has been correctly inserted. The fastening pin 50 has a grip 50 a which is transverse to the pin axis and is aligned in a first direction on insertion of the fastening pin 50. In this orientation, a longitudinal pin groove 50 b receives a guide pin 53 which, when the fastening pin 50 has been completely inserted, rests in an annular groove 50 d so that the fastening pin 50 is rotatable through 180° in a locking position. A locking check 47 (cf. FIG. 2) envisages that the fastening pin 50 can be checked in the locking position. For this purpose, the grip 50 a is preferably provided with a locking magnet 50 c which, in the locked state or in the locking position, is adjacent to a locking Hall sensor 54 in the pressing tool. If the locking Hall sensor 54 detects the locking magnet 50 c, the locking pin 50 is in the locking position. if the check for locking is negative, a warning signal is triggered without the start procedure of the pressing tool necessarily being interrupted. Of course, it is also possible to use, for example, an inductive sensor instead of the Hall sensor.

[0016]FIG. 2 shows a pressing process for tightly pressing on sleeve-like fittings 32 a using a pressing tool which actuates the clamping movement of at least one cheek plate 51 a or 51 b via a piston rod 6 and a transmission device (cf. FIG. 1). By means of an on/off switch, the pressing tool is switched on in a switch-on step 41. A self-test, start test and service test are then performed in an initialization step 42. Before a pressing process 44 together with determination of operating parameters can be triggered in a triggering step 43, it is necessary, in a repeatable second step, to determine whether the pressing tool is ready for triggering a pressing process 44. In the second step, a pressing jaw presence check 45 is carried out until a pressing jaw 51 (FIG. 1) has been inserted. As long as no pressing jaw 51 is present, an acoustic and/or optical warning signal 45 a is triggered or maintained. If, after a delay, a pressing jaw 51 still has not been inserted, the pressing tool can be switched off by a time-lag means 45 b. If a pressing jaw 51 has been inserted, an allocation check 46 is carried out after a delay, as described in publication EP 0941813-A1, in order to assign a piston position range value to the inserted pressing jaw 51. If allocation information is absent, a standard range allocation 46 a is performed. As a further checking step prior to enabling the triggerability of a pressing process 44, a locking check 47 is preferably carried out in order at least to trigger a warning signal 47 a if a fastening pin is not secured. After these checking steps have been successfully carried out, the pressing tool is ready for triggering a pressing process 44. If the fastening pin 50 (FIG. 1) has not been properly locked, the ready state for the pressing process 44 is enabled only after a delay by a second time-lag means 47 b, in order to give the operator the possibility of locking the fastening pin 50. If the pressing process 44 is not triggered within a specified time, a rest time monitor 43 a checks whether the device has remained switched on for a specified maximum rest time without a pressing process 44. If the maximum rest time has not yet been reached, the device runs through the second step or the checking steps 45-47 again. If the maximum rest time has been reached, the pressing tool is switched off. Before it is possible to trigger a further pressing process 44, the checking steps 45-47 must be carried out again. 

1. Pressing tool for tightly pressing sleeve-like fittings (32 a) onto two pipe ends for the purpose of connecting the two pipes, comprising a hydraulic cylinder device with a fork-like connecting part (7), a pressing jaw (51) which can be interchangeably fastened in this connecting part (7) by means of a fastening pin (50), and a drive motor for actuating a piston rod (6) as an actuating member for moving at least one cheek plate (51 a, 51 b), characterized in that a presence sensor (52) for the pressing jaw (51) is provided, which delivers a signal by means of which, in the event of an absent or incorrectly inserted pressing jaw (51), the initiation of a pressing process (44) can be prevented or an initiated pressing process (44) can be terminated.
 2. Pressing tool according to claim 1 , characterized in that the presence sensor (52) is one which measures without contact, preferably one which measures inductively, and makes it possible to detect the presence of the pressing jaw (51).
 3. Process using a pressing tool according to claim 1 , the clamping movement of at least one cheek plate (51 a, 51 b) being permitted via the piston rod (6) and a transmission device, characterized in that, after an initialization step (42), in which the self-test, start test and/or service test are carried out, a pressing jaw presence check (45) is carried out in a repeatable second step, before a pressing process (44) is made triggerable, and, with an absent or incorrectly inserted pressing jaw (51), a warning signal (45 a) is output and—optionally after a repetition of the pressing jaw presence check (45)—the pressing process is not initiated or the initiated pressing process (44) is switched off after a delay if the pressing jaw (51) still has not been correctly inserted at this time.
 4. Pressing process for tightly pressing sleeve-like fittings (32 a), using a pressing tool according to claim 1 , the piston rod (6) actuating the clamping movement of at least one cheek plate (51 a, 51 b) via a transmission device, characterized in that, after an initialization step (42), in which the self-test, start test and service test are carried out, a pressing jaw presence check (45) is carried out in a repeatable second step, before a pressing process (44) is made triggerable, and, in the case of a correctly inserted pressing jaw (51), an allocation check (46) is carried out after a short delay in order to assign a piston position range value to the inserted pressing jaw (51), and a locking check (47) is carried out as a further checking step before enabling the triggerability of a pressing process (44), in order to trigger at least a warning signal (47 a) if a fastening pin (50) has not been secured, and then to initiate the pressing process (44).
 5. Process according to claim 3 , characterized in that the pressing jaw presence check (45) detects an inserted pressing jaw (51) in a non-contact, in particular inductive, measuring step and that the locking check (47) preferably with a magnetic field measurement by means of a Hall sensor—detects the fastening pin (50) in its secured position.
 6. Process according to claim 3 , characterized in that, if the fastening pin (50) is not secured, the continuation of the pressing process (44) is postponed for a certain time, optionally after a repetition of the locking check step (47), if the fastening pin (50) still has not been properly locked at this time. 